The following figure shows the structure of the hydrostatic fluid coupling. In order to reduce the overload coefficient of the fluid coupling and improve the overload protection performance, there is a high torque coefficient and efficiency at a high transmission ratio. Therefore, the structure is different from the ordinary type fluid coupling. Its main feature is the symmetrical arrangement of the pump impeller 2, the turbine impeller 3, and the baffle 5 and the side auxiliary chamber 4. The baffles are mounted at the turbine outlet and act as diversion and throttling. This fluid coupling works under partial filling conditions.

This kind of hydraulic coupler, in the high-speed transmission ratio, the side auxiliary cavity has little oil, so the transmission torque is large; while in the low transmission ratio, the side auxiliary cavity has more oil, so the characteristic curve is relatively flat and can be compared. Good to meet the requirements of the working machinery. However, it should be pointed out that since the auxiliary chamber on the liquid inlet and outlet side is slow to respond to changes in load, it is not suitable for load change and work machines that frequently start and brake. Because this type of fluid coupling is often used in the transmission of a vehicle, it is also called a traction type fluid coupling.